Corderoite is an extremely rare mercury

Mercury (element)

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...

 sulfide

Sulfide

A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...

 chloride

Chloride

The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...

 mineral with formula Hg₃S₂Cl₂. It crystallizes in the isometric crystal system. It is soft, 1.5 to 2 on the Mohs scale, and varies in color from light gray to black and rarely pink or yellow.

It was first described in 1974 for occurrences in the McDermitt Mercury mine in Humboldt County, Nevada

Humboldt County, Nevada

Humboldt County is a county located in the U.S. state of Nevada. As of 2007, the population was estimated to be 18,052. Its county seat is Winnemucca.The county was the site of an arrest in 2000 that led to the U.S. Supreme Court decision Hiibel v...

. The name is from the old name of the mine, the Old Cordero Mine.

Structure

Corderoite has crankshaft chains that are crosswise linked by additional Hg²+. The bond distance between the cation Hg and anion S is 2.422 Angstroms. It has two angles, Hg-S-HG= 94.1º and S-Hg-S= 165.1 º. Various sulfide halides of
Hg share the feature of being face-sharing [HgS2X4] −6polyhedral, as corderoite’s polyhedra X=Cl.

Geologic occurrence

The main occurrence of corderoite in the type locality

Type locality (geology)

Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....

 is in the Upper Miocene

Miocene

The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 playa

Sink (geography)

A geographic sink is a depression within an endorheic basin where water collects with no visible outlet. Instead of discharging, the collected water is lost due to evaporation and/or penetration...

 sediments within a thick zone, around 5–7 meters, sub parallel to bedding. Lake sediments including altered rhyolitic

Rhyolite

This page is about a volcanic rock. For the ghost town see Rhyolite, Nevada, and for the satellite system, see Rhyolite/Aquacade.Rhyolite is an igneous, volcanic rock, of felsic composition . It may have any texture from glassy to aphanitic to porphyritic...

 tuff

Tuff

Tuff is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Tuff is sometimes called tufa, particularly when used as construction material, although tufa also refers to a quite different rock. Rock that contains greater than 50% tuff is considered...

 and ash

Volcanic ash

Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...

 were deposited on the Tertiary rhyolitic volcanic rocks. Corderoite occurs as isolated grains or with cinnabar as replacements. Corderoite occurs as a low temperature supergene

Supergene (geology)

In ore deposit geology, supergene processes or enrichment occur relatively near the surface. Supergene processes include the predominance of meteoric water circulation with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary sulfide ore minerals and...

mineral.